If there were things such as speed hacks, I bet people would be talking about them all over the place. There are some settings that will earn some frames in some games by either enabling/disabling (like copy EFB). Otherwise, I'm sure there would be possible to make many game specific speed hacks that causes mess in other games, the team just don't want a bunch of those.

There are no speed hacks. Esentially make sure you have Dual Core enabled (for most games). You can also turn off Enable Other Audio (Throttle). Then just play with graphic settings and see if you can gain any improvements. But there isn't any magical tricks you can do to make things go a lot faster.

Actually certain games have speed hacks that will work. There usually some weird code you have to put in the ini file to get to work but I have no idea what games they work for. Most of the games have them added by default.